Because you reject all possible affirmative claims about where in spacetime the free electron is present. You don't accept it is unsharply, ontologically everywhere that it's quantum state has non-zero amplitude (or amplitude in excess of |0>). You don't accept the Bohmian idea that it is sharply at a single (epistemically uncertain) point. You claim quantum theory is just a theory of detector clicks.Why should my statement above imply such obvious nonsense of non-existence of free electrons?
Therefore, you don't believe free electrons are present in spacetime, but somehow pop into spacetime when forming macro objects, and you want to start using chemistry, materials science etc.